This invention relates to combination locks of the type having a hasp-engaging latch, which is moved from a hasp-engaging position by means of a movable actuator in order to release the hasp and open the lock. Such locks employ combination locking means, such as combination tumblers, dials or the like, associated with the actuator to prevent the actuator from moving the latch out of engagement with the hasp except when the combination locking means is on-combination.
In locks of the above type, the latch may be spring biased to return to its hasp-engaging position when the hasp is released. Accordingly, in locks where the latch and actuator are rigidly connected, in order to re-engage the hasp with the latch, it is necessary for the lock to be on-combination so that the latch and actuator can be moved by the hasp against the spring bias as the hasp is pressed into position.
It is an advantage, for security reasons, to provide a facility whereby the combination locking means can be scrambled to an off-combination setting when the hasp is disengaged and whereby the hasp can be re-engaged while the lock is still off-combination. To this end, it has previously been proposed to provide a connection between the latch and actuator which allows the latch to be moved away from its hasp-engaging position independently of the actuator, through pressure exerted by the hasp when it is pressed into place, the latch being spring biased to snap into its hasp-engaging position when the hasp is pressed fully home. The connection between the latch and actuator is still such as to allow withdrawal of the latch from engagement with the hasp in the conventional manner by movement of the actuator, only when the lock is on-combination.
With locks having the above-described scrambling facility, however, since the latch is not itself positively locked when the hasp is engaged, it may be possible to open the lock even when it is off-combination, by manipulating a small tool or suitably bent wire under the hasp plate and thereby moving the latch out of hasp engagement, or by striking a blow against the lock in a suitable direction to move the latch. The present invention seeks at least to minimize and preferably to avoid this possibility.
It is a principal object of the invention to provide a combination lock of the character described, which has a facility whereby the hasp can be engaged with the latch even when the lock is off-combination, by movement of the latch independently of the actuator, but wherein the latch effectively cannot be forced out of engagement with the hasp independently of the actuator when the hasp is engaged.
Another object of the invention is to provide a novel form of combination lock employing combination dials and sleeves for controlling movement of an actuator, a hasp-engaging latch connected to the actuator for movement therewith to open the lock when the sleeves and dials are on-combination and wherein the latch can be moved away from a hasp-engaging position independently of the actuator only when the hasp is disengaged.
Yet another object of the invention is to provide a dial and sleeve type combination lock, for example of the character disclosed in U.S. Pat. No. 4,123,923 to Bako, issued Nov. 7, 1978 and commonly assigned herewith, with the facility whereby the hasp can be engaged with the latch even if the dials are off-combination but in which the latch effectively cannot be forced out of engagement with the hasp when the hasp is engaged.